Manufacture of aluminum and its alloys.



a source of the carbon, and convert it into duction of the sulfate, which otherwise UNITED STATES Parana OFFICE.

HEINRICH F. D. SCHWAHN,

OF BELLEVILLE, ILLINOIS.

MANUFACTURE OF ALUMINUM AND ITS ALLOYS.

964,566. In Drawing.

To all whom it may concern:

Be it known that I, HEINRICH F. D. Scuwanx, a citizen of the United Stat%, and resident of the city of Belleville, in the county of St. Clair and State of Illinois, have invented certain new and useful Improvements .in the Manufacture of Alumipum and Its Alloys, of which the following is an exact specification.

My invention consists in an electric proc- & for the production of aluminum from. sulfate of aluminum, which latter can be produced very easily and cheaply from any aluminous ore by my process, Letters Patent No. 752,927, February 23, 1904, and the object of my present invention is to produce aluminum from said sulfate of aluminum, and free of carbon or aluminum carbid, which if present in the metal to any extent will render it useless for-any p ose.

My invention, moreover, consists incsucb other features, steps and methods as will be hereinafter more fully set forth and pointed out in 't-he claims. i

In accordance with my invention the sulfatcof aluminum, taking an anhydrous sulfate of aluminum of the formula A1,,(SOQ, as a type, is diffused, at high beats, with carbon in quantities proportioned to the oxygen contained therein, thereby'produca combination corresponding a proximately with the formula Al (SO,) .L and than passing through such combination an electric current, suitable in the presence of a solid or gaseous flux or both, while excluding the outer air by a usitable reducing and which obviously can be also accom-. plished by the resultant spent gases.

As a source of the carbon, to combine with the sulfate of aluminum, I may use pitch, asphaltum, tar, petroleum or the like, wood charcoal, carbonaceous matter or an other substances including gases capable 0 giving up carbon at their decomposition into their constituent elements if heated with the anhydrous sulfate of aluminum at a temture of about 9Q0 C. or at its incanesccnce; when such nascent, carbon will readily combine with said sulfate by its t afiinity for the same, especially when a substance such as pitch has een used for an electric resistance conductor or electroivte, thereby permitting an electrical rc- Specification of Letters Patent.

Application filed December 7, 1908. Serial No. 466,255.

said container or electric furnace.

would not be possible. It is understood that Patented July 19, 1910.

the power said heated or glowing porous aluminum sulfate possesses of appropriating carbon evolved from intermingled Sub stances or permeating gases is a case of surface attraction by the forces of catalysis innate to porous substances, and whereby the resultant amorphous carbon at the given high temperature of about 900 C. is absorbed and combines mechanically with the sulfate which becomes thereby electrically conductive or an electrolyte and conse-' quently reducible by an electric current of suliicient volume to produce a resistance upon said electrolyte and bring it into in candescence and generate heat by which the sulfate with the aid of the carbon combined therewith is reduced to the metal in conjunction with the sulfur radical of thesulfate to sulfur which is recovered as a lay-product. The said electric reduction I carry out by passing an electric current through said re sistance conductor or electrolyte, preferably; in'conncction with. a flux, as such forinstance, fluorids of the alkalies or alkaline earth metals, while excluding the outer air from the container, suitably by charging a reducing-gas such as regenerated producergas, a highly diluted gas by nitrogen, into With this reducing gas may be also chargedta gaseous flux, as such for instance, fluorin, suitably in form of hydro-fluoric acid vapors, suitably prepared, as usual, from fluor spar and sulfuric acid in a suitable substantially closed auxiliary container, suitably arranged to -perform the evolving of the fluorin gradually, and conve it y means of suitable tubes or pipes to t e supply-pipe of the reducin -gas .to 'coinming with previous 0 its charging into the smelter furnace. The object of; using eous flux is to assist the de osition of the reduced metal for its purification by the fluorids used for a flux, and it has been noticed that by introducing the gaseous flux the solid flux remains constantly more liquid. \Vithout the use of the gaseous flux the solid flux is apt to become mushy in course of time thereby preventing thedeposition of the reduced metal to a. great extent, and consequently requiring a re newal of the solid flux. The proportion of the fluorin gas to the reducing-gas may be about like 1 to 11000 in volume, and only small quantities of such agas mixture is required- However, all the spent gases will e therethis gasbe confined after their discharge from the smelter furnace for the" recovery of the sulfur, reduced from the sulfur radical of the sulfate by its containing carbon. The remaining spent gases may be fired or carriedaway and suitably used for heating, power or any other purpose.

In carrying out my invention in the preferred form and most suitable manner for commercial purposes I procure a calcined sulfate of aluminum, preferably of about the formula Al (SO,) and mix it with pitch in preference of any other substance containing carbon, and 1 preferably use about 20-25 parts of said pitch to about 1G0 parts of said calcined or anhydrous sulfate of aluminum all by weight. The mixing of said sulfate with pitch can he done very easily in the cold, when the pitch will be brittle, by pulverizing both together in a suitable puddle mill; or said mixing may be done while both, the sulfate and pitch, are hot from previous heating, and therefore only the sulfate need to be crushed or pulverized, for reason that-the pitch will be liquid when hot. Then 1 subject such 1nixtures of sulfate of aluminum and pitch to a high red or yellow heat or about 900 C. in a substantially closed container. The object of having this carried out at high heats and in a'closed container is to completely crack up the pitch, on its vaporization, into its constituent elements and free the carbon, and retain the same for its combining in definite proportion with the sulfate, at the prevailing high temperature, and produce the desired electric resistance material or electrolyte, which is of a coke-like appearance and to some extent of metallic luster. This material is subjected, suitably in a broken or crushed condition, and mixed with one or theother of the above named fluxes or a combination of the same, suitably also in a crushed condition, to the infiuence of an electric current in a suitable electric furnace, while excluding the outer air by means of a suitable reducinggas such as regenerated producer-gas, which may be mixed also with said gaseous flux or hydrofiuoricicid vapors and produce the metal free of aluminum carbid. For convenience however, and to facilitate the procedure I preferably carry out the entire process in one continuous operation, or nearly so, and

referably in my improved electric furnace,

ing the subject matter of an application for Letters Patent Serial No. 485,503, filed March 9A, 1909, allowed Nov. 30, 1909, and which I consider as indispensable for this purpose, to getthe best results.

In carrying out the process in a coutinnous operation and in the preferred form I proceed as followsz-I mix, as above described, said sulfate of aluminum and pitch, and lcaye it in the green state, and use the hcreinabove described electric furnace previously and sufliciently heated in the'usual way by means of an aluminum ring and the electric current. so that when the fused aluminum and flux is charged for the starting of the furnace the same will not chill, and consequently interfere with the contin- HC-tiOII of the operation, then I charge first some ready made electrolyte and follow with the green mass or mixture of sulfate -and forming a coherentbody, and as fast as the green mass descends into the hotter parts of the. electric circuit below. of which said body of resistance conductor then forms a part and produces more heatfor its continuous production, and reduction to the metal. The solid flux is perferably added in this case in a crushed state and spread upon the previous charge of the green mass. -The gaseous flux with the reducing-gas although desirable may be omitted in the production of alloys.

During the electric smelting the currentacts first and principally upon the electro- 0 lyte as the highest resistance material of the charge, and secondarily only on the fused metal and flux, simply retaining the same in a fused condition. And if the process is carried out in my aforesaid improved electric furnace, which I prefer to use for a container, the rotating or circulating action of the secondary electric current on the fused metal and flux, incidentally takes in continuously the reduced metal for its deposition, and final purification by said flux, some of which will flow out with the metal on its tapping, into the usual ladle, where they may separate by settling, one or the other on. its bottom in accordance with the kind of flux used, and which may be made use of again as long as such flux retains its fusibility, that means becomes not, overloaded with impurities, which may have been contained in the sulfate, or which may have been conveyed to the metal from the material of which said furnacehas been constructed.

For the production of alloys suitable quantities of the metals to be alloyed--with the 1 aluminum may be added to the respective chargcs into the furnace, and in definite PIIPPUPUOHS to produce a certain desired :1 Joy The npderlymgprinciple of this process consists in combining the sulfate of alumihave the same object viz: producing the proportion and then only at high tem er- V reducing the same to the metal, and consistv nascent carbon evolved from carbon contaim stance mixed therewith as repeatedly denum with nascent or amorphous carbon evolved from carbon containing substances including gases, mixed or charged with the sulfate into a substantially closed container and subjected to a high temperature, and then subjecting the resultant electrolyte to the action of a suitable electric current; and which differs entirely from any former attempts made in reducing aluminous compounds such as sulfate and alumina by furnace heat or that of an electric current with the aid of carbon or a carbon containing subscribed in numbers of patents. I am aware of these former practices, and although they metal they are inoperative and without practical success; it is only the nascent or amorphous carbon which will and is able to combine with the sulfate of aluminum in defined utures or about 900 C. to produce an e ectrolyte or resistance conductor for its electrical reduction, and which I claimas my discovery and invention.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The improved manufacture ofvaluminum which consists in the method as herein described for producing an electrolyte and in in combining at a high temperature a de ydrated sulfate of aluminum with carbon evolved at said high temperature from carbon containing substances including gases in the presence of said sulfate of aluminum, and then reducing the resultant electrolyte and producing metallic aluminum by the influence exerted by an electric current upon said electrol vie, while recovering the resultant sulfur as a by-product, substantially as set forth.

2. The improved manufacture of aluminum which consists in the method as herein described. for producing anelectric resistance conductor from anhydrous sulfate of aluminum by combining such sulfate with ing substances includin gases while subjecting the same with said sulfate of aluminum to a temperature of about 900 C., and then roducing the metallic aluminum by the in uence exerted by electric currents v upon the resultant combination of anhydrous sulfate of aluminum and carbon being said electric resistance conductor, substantially as set forth.

3. The improved manufacture of aluminum which consists in the method as herein described for producing an electric resistance conductor from dehydrated sulfate of aluminum by combining such sulfate with amorphous carbon evolved from carbon containing substances incl'fding gases the resultant product of which corresponding in its composition ap roximately with the formula l-LIJSQ) and then subjecting said product, being said electric resistance conductor to the influence of an electric current, while charging a suitable reducing gas into i container and producing the aluminum and sulfur, substantially as set forth.

4. The imprmedmanufacture of aluminum, which consists in the method as herein described for producing an electrolyte and reducing the same to the metal, and consisting in combining at a high temperature an anhydrous sulfate of aluminum with carbon evolved' from. pitch, charged with said sulfate, and then reducing the retrio current for the reduction of the metal,

while excl ding the outer air by a -:cducing gas to which a fiuorin containing gas is added for a flux.

In testimony whereof I have hereunto set my hand.

nnmaion F. n. *SCHWAHN.

W'itnesses:

EDWARD W. Vv'ssr, J r., Geo. W. Drvnannnvc. 

